Apparatus for sending and recording time impulses



March 3, 1942.

BDASTING MCHIN o. F. RlTzMANN 2,275,316

APPARATUS FOR SENDING AND RECORDING TIME IMPULSES Filed June 26', 1941 2 Sheets-Sheet l RGORDERS Q f@ ,7 57

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APPARATUS FOR SENDING AND RECORDING TIME IMPULSES FiledJune 2e, 1941 2 sheets-sheet 2 T v vvvvvvvvv .v 2@ n@ fn 20 RECORDER le? r'y?. 7C). /46 25,7 Y @P @e5 Syvum O. I Rif/'z mara 7L,

PRIORART Patented Mar. 3, 1942 UNITEDd STATES PATENT. OFFICE APPARATUS ron sENmNG'ANn astronomo 'rma nurULsEs Otto F. Ritnnann, Aspinwall, Pa., assigner to Gulf Research- Development Company, Pittsburgh, Pa., a corporation of Delaware Application June 28, 1941, Serial Noi 399,923

v 4 Claims. (Cl. 23h-36.5) 'Ihis invention relates to improvements in ap which the necessity for provision of a blasting paratus for sending and recording time impulses. machine switch is obviated.

In seismograph prospecting. a charge oi' dyna- These and other objects are achieved by the mite ithe shot) is iired electrically at some point provision of apparatus including a coupling in the earth. The articial seismic waves gener- 5 means in circuit with a source of energy and an ated thereby in the earth are detected electrlinterrupting means, so that on interrupting the cally at one or more points spaced from the shot circuit a current impulse is induced in the couand recorded photograplucally. For best results, plins means. an oscillosraphic recorder. and o it is desirable to indicate ,very accurately on the `networlr between the coupling means and the reseismic wave record, the exact instant oi time m corder having shunt and series branches and at at which the'shot explodes. In the ordinary sysleast two half-wave rectiers, each in a different tem a blasting machine (a, manually operated branch of the network, and so connected as to D. C. generator) is used to re an electrical blastallow transmission to the recorder Of pulses 0f ing cap embedded in the dynamite, and the cap the polarity resulting from interruption of the is cmmected m cil-wit, diremy or indirectly' with 15 circuit while obstructing transmission to the rean electrical oscillcgraph recording device ar- @Order 0f Signals 0f Opposite POlal'ity- The net 1'@- rgnged to produce a mark on the Seismic wave sult is a perfectly clear and unidirectional immuun-@ The circuit meeting the blasting mb pulse as recorded, despite the ragged character of chine. cm3 and oscmgraph is normally open, the original impulse. Inthe embodiment wherein While the masi-,mg 'machine handle is being gothe source oi energy is a blasting machine, the pushed down. Near the bottom of the stroke, a invention makes possible elimination of the cus? switch is closed, completing the circuit, whereby tomar? switch at the blasting machine if desired' current builds up rapidly in the circuit. When with marked advantage' the cap'explodes the circuit is broken and the In the accompanying drawings there are shown current drops to zero. The shot firing instant E@ dia'gmmmatica'uy ve xa'mples of apparatus 1S read on the record as he point where the cur within the purview ofthe invention and schematic rent begmtodmp reproductions of typical time records obtained hereby. Inthe drawings This simple system does not give as dente t an indication ci the exact instant of the ex- Fig l is a dmgmm of a'cmp1ete apps'mt'us plosion as lsdesired. The time indication on the 30 including the tme'impulse ,transmitting circuit Y corresponds tothe actual instant of explosion.

- m t i i and recorder, gg, gm shalertlueveml sufra Fig. 2 is a reproduction oi a portion of the po y timing record obtained with'the apparatus of ripples, quarers or wiggles, and a gradually iall- Fig 1 t ingportionwhich likewise contains irregularities.

It is dimcultto tell just which part oi the maris 35 apausoiglam of a modmed form of the Fig. t is a reproduction of a portion of the @memes the highest amplitude Part 0f the timing record obtained with the apparatus of mark does not correspond to the instant oi err- M 3, ploson' Shm't circumng of the cap leads my 40 Fig. 5 is a chart showing a typical rectiiier give rise to serious spurious indications. To make characteristic curve for ai in und r ming th matters worse, the character of the record. varier. invention. d e s e with dierent makes and designs of caps, and mgf is a di@ am of the s tem of 1 even with dinerent batches of caps of the same as applied to chmgrogrgphy, ys Fig make. Y 45 Fig. 7 is a reproduction of' a portion of the Among the objects of the invention are thc timing record obtained with the apparatus of provision oi an improved apparatus for transmit- Fm s, ting and recording the exact instant 0f time mi Fig. 8 is a chart showing the character of the which a shot or other .phenomenon takes place. time signals of the apparatusgf Fig, 6 9,8 transin a deiinite-and unambiguous manner; to pro- 50 mitted by radio. vide such an apparatus including a circuit in Fig. 9 isa diagrammatic showing cf a modificawhich reversals of current in an impulse being tion of the apparatus of Fig. l, makinguse of a recorded are prevented, so as to secure a simple dlfi'erent network between the coupling meansV and regular mark; and the provision ci such cirand the recorder, cuits in combination with blasting machines in 5t Fig. 10 is a similar showing of another modiiication, with a modified network between the couplingmeans and the recorder,

Fig. 11 is a showing illustrative of typical blasting impulses as recorded in prior art systems, and Fig. 12 is a diagram of a modification of the apparatus of Fig. 3, employing a battew as a source of energy and employing a plurality of series and of shunt rectiflers.

Referring to the drawings and inparticular to Fig. 1, a blasting machine 2@ of known type is provided, comprising a D. C, generator 2l operable by a rack 22 having a handle 23. Upon pushing down the handle, a direct current is developed in leads 2li from the generator, which may have a peak voltage -output of 200 to 300 volts atno load,.and a maximum current output of 2 or 3 amperes. The machine is adapted to fire a shot,

The time indication shown in Fig. 2 ispractically an ideal record, as it not only corresponds very closely to the exact instant of initiation of the explosion, but also it is very definite and unambiguous in character. There are practically no trembiings or' Wiggles in the record because the rectiners permit iicw of current in only one direction. By Way. of comparison, Fig. 11 shows at 340 a typical shot moment impulse as recorded by conventional systems, without the improvement of the present invention.

If rectifier `31 were 100 per cent efficient, that is,if it passed zero current in the opposite direction from the current direction it is designed to transmit, there would be no point in providing shunt rectifier 38. But since rectiiiers as at present known are not perfectly efilcient, rectilier 38 is included as shown and described.k If

by a motor 33. Upon electrical energization of the oscillograph element, a trace i3 is produced on the moving photographic paper which appears as a black mark when the paper is developed. A transformer Eid is arranged with its input in series with the cap 21 and the blasting machine. The primary of the transformer together with these elements completes a primary circuit. The output oi the transformer is applied through a pair of leads and 86 to the oscillograph element, forming a'secondary'circuit. Leads 35 and 38 in practice may take the form of a telephone line several hundred yards long. A rectifier 31 lis arranged in lead 35, to permit flow of current in only one direction as shown, and a second rectiner 3@ is connected in shunt across the transformer output as shown. A resistor 3d is shown connected in shunt across leads 35 and `38,*to limit to a safe value the current applied to the sensitive oscillograph element.

The operation of the system is as follows: Upon pushing down handle 23 a current of progressively increasing magnitude is developed in the primary circuit comprising leads 24, the primary of transformer 34, and the cap. The direction of the current ow is indicated by arrow 4B. However, no ow of current can take place through the oscillograph element 30 because of rectiner 31 which permits current flow only in the direction indicated and vstops reverse ow.

Accordingly, the trace I9 on record 22 remains a straight line. Rectifier 33 vbypasses current developed in the transformer secondary and serves in eect to short circuit the oscillograph element; When a sufcient current ls developed by the blasting machine to explode the cap, the cap res, the shot explodes and the primary circuit is broken. Instantly the collapse of the magnetic field in transformer 34 induces in leads 35 and 38 a high voltage of reverse polarity. This voltage is not s'hort-circuited by rectier 3l and it is passed by rectiiier 31. It appears across resistor 39 with the polarity indicated as shown and actuates oscillograph element 30. An abrupt Jerk occurs as shown at 40 in Fig. 2, which shows I a portion of record paper 32 to an enlarged scale. The induced current very 'quickly dies down and desired, a plurality of rectifiers can be' used in series, at 31 or 38 or both,to secure more eiiicient unidirectional transmission; Such a modification is shown in Fig. 12, in which two series rectiiers 37 and 231, and two shunt rectifiers 3&3 and 238, are provided, in a secondary circuit otherwise like that of Fig. 3. The rectiflers are arranged in the secondary circuit as shown' and described so that they need carry less current than that owing in the primary circuit and also so that advantage is taken of vtheir selective current amplitude characteristics as4 described Vin detail below. s

The transformer 3 is advantageously a stepup transformer. A voltage step-up ratio of about 8:1 is'especially advantageous. The stepped-up signal is easier totransmit long distances, and currents are lower in the secondary circuit. However, in lieu of a transformer a simple in- -ductance coil can be employed.

Fig. 3 shows a modification of the apparatus of Fig. l which is adapted for use with switch type blasting machines. The blasting machine i211 is like that shown" in Fig. 1 except for having switch contacts 4S an'd 48, which are adapted to close when the handle is pushed down almost, but not quite, to the end of its stroke. Switch '45, 48 is connected in series lwith one of the leads 24 as shown, so that the circuit through the cap is normally open and is not closed until the machine handle is almost all the way down. In Fig. 3 the transformer is dispensed with and a simple choke coil 41 is arranged in shunt across leads 35 and 36 to serve a similar function. Fig. 3 shows a radio transmitter 50 and receiver 5I interposed between the blasting machine and the recorder; an arrangement sometimes used in seismog'raph prospecting when the shot and the recordersv are several miles apart. If desired, the connection can be direct as in Fig. 1.

In operation, as the machine handle is pushed down the whole circuit is dead until contactor 45 engages contactor 43. 'I'his applies the blasting.

machine output to the cap and explodes it. During the time current is flowing to the cap, the recorder is short circuited by rectifier 38 as described in connectionjwith Fig. 1. When the cap explodes it breaks the circuit and a surgecurrent oi reversed polarity is developed in coil 41, which ows through rectifier 31 and the recorder oscillograph 3l, making a mark on the record which appears as shown in Fig. 4 at 48.- This record mayhave a few minor irregularities as'indicated at 4l and 49, but these are of negligible importance. The explosion instant is definite and is very easy to read. The timing mark is uniform.

the trace returns to normal as shown in Fig. 2. despite suchirregularities viin *theblasting mathe true break of the primary circuit is recorded.

n the whole I regard the system of Fig. 1l as the best embodiment, because it dispenses with the usual blasting machine switch. The switch has been a source of trouble because its contacts are apt to get dirty and corroded. and this, together with arcing at the switch contacts, sometimes produces spurious indications on the record. However, if it is desired to employ a switch, the system of Fig. 3 gives time records which are much superior toanything` that can be obtained with the ordinary systems. In Fig. 3 the blasting machine can be replaced by a battery if desired, in the manner shown in Fig. 12, a switch M6 being provided as shown to close the cap circuit.

For rectiers 31 and 38 I ordinarily employ copper oxide rectiiiers, `because of their simplicity, ruggedness, compactness and convenience, but other types of rectiers can be employed if desired.

Fig. shows the characteristics of rectiers of the copper oxide type (which characteristics also apply to rectifiers of many other types) and illustrates how the results of the invention are achieved. Upon application of a relatively high voltage such as V to the rectifier in a forward direction, that is, in the polarity which the rectiy' iler is adapted to pass, a relatively large current I is passed, and the resistance of the rectier under these-conditions may be only a few ohms.

If, however, a small voltage is applied, in either direction, the current. owing through the rectifier is very small; the resistance of the rectifier to iiow of small currents may be as much as hundreds or thousands of ohms depending on the magnitude of the current. In the reverse direction even large voltages meet resistance oi' a thousand ohms or more. The rectier 31 is chosen in relation to the other circuit constants so that it will function on that part of the characteristic curve which does not allow the small current fluctuations to pass, but which does pass the large current surge due to shooting the cap. This accounts for the suppression of undulations in the records of Figs. 2 and 4. The rectifier is selective to amplitude as well as to polarity o1 electrical signals applied to it, in that it transmits high voltages very much more freely than low voltages. Full advantage is taken of this property as the rectiilers are connected into the secondary (high voltage) circuit.

The transformer, rectiflers and resistor are conveniently mounted in a suitable housing (not shown) attached to the blasting machine.

The rectiiiers can be arranged in manner other than the shunt and series connection of Figs. 1 and 3, the essential being to have them connected. each in a diierent branch of an electrical network having shunt and series branches, in such manner as to allow transmission to the recorder of pulses of polarity resulting from interruption of the primary circuit while obstructing transmission to the recorder ot signals of opposite polarity. Figs. 9 and 10 show optional circuits. In Fig. 9 the network between coupling of the network, the series branch including a series resistor 339.

The invention is applicable to other utilizations i than `recording the instant of firing of a dynamite charge. It is desirable in many arts to produce a sharp and unambiguous time record on a chart,

etc.; a sharper impulse than can be secured merely by opening or closing switch contacts. Fig. 6 shows how the invention is applied to chronography, where it is desired to produce marks on a record at regular spaced intervals of time. A chronometer 52, which may be a clock for example, is arranged to close and open at regular intervals a switch comprising contactors 53 and 54, by means of a ca-m 55. VThe switch is connected in series with a battery 56, a resistor 51 and `the primary of a transformer 34 in circuit with a recorder as in Fig. 1. Upon actuation of the chronometer a seriesof time marks is produced as shownat |40 in Fig. 7. 'I'he marks |40 correspond to'the breaks `(openings) ofswitch 53, 54. Themakes (closings) ofthe switch are largely suppressed by the action of rectiers 31 and 38, and appear only as very small jogs 58. The apparatus of Fig. 6 not only gives remarkably sharp time marks, but also, by suppressing the makes of the chronometer switch eliminates an annoying source of confusion. Fig. 8 shows how the time record may appear after transmission by radio. The sharp character of the impulses is largely preserved as indicated at 240.

What I claim is: l i

1. An apparatus for sending and recording clearly a current impulse oif,l irregularly uctuating character. comprising a circuit including an inductive coupling means and means for producing an abrupt change in current in said circuit whereby on such abrupt change a current impulse is induced im the coupling means, said impulse being subject to irregular fluctuations, anl oscillographic impulse recorder arranged to receive and record the induced impulse, said recorder being constructed and arranged to record the characteristic wave form of impulses applied means 34 and the recorder has resistive shunt branches 39, |39 and series branches on either side of resistor it; in separate series branches .are two rectiers 81 and 631. In Fig. 10 rectiers to it, an electrical network having shunt and series branches arranged to transmit pulses from the coupling means to the recorder and atleast two half-wave rectiers each in a diierent branch o! said network and each connected to allow transmission to the recorder of pulses of the po larityresulting from the abrupt change in current in said circuit and to obstruct transmission to the recorder of signals oi' opposite polarity, whereby the impulse as recorded is of sharp unidirectional character.

2. An apparatus for sending and recording a current impulse of fluctuating character produced by the interruption of a blasting circuit, comprising in combination van inductive coupling means connected in a blasting circuit whereby on interrupting such circuit a current impulse is induced in the coupling means, a seismograph type oscillographic impulse, recorder arranged to receive and record the induced impulse, said recorder being constructed and arranged to record the characteristic wave form of impulsesapplied to it, an electrical network having shunt and series branches arranged to transmit pulses from the coupling means to the recorderland at least two half-wave rectiers each ina dierent branch o f said network and each connected to allow transmission to the recorder oi.' pulses of the polarity'resulting from the interruption of the `blasting circuit and to obstruct transmission to the recorder of signals of opposite polarity, whereby the impulse ias recorded is of sharp unidirectional character.,

3. An apparatus for sending and exhibiting a current impulse of irregular fluctuating character produced bythe breaking of a blasting circuit, comprising in combination an inductive coupling means connected in e blasting circuit whereby on breaking of such circuit a current impulse is induced by the coupling means, impulseexhibiting means arranged to receive the induced impulse. a copper oxide type rectiler connected in the output side of the coupling means in series relation thereto so as to pass induced current in one direction only, of polarity resulting from breaixing of said blasting circuit and to obstruct current of opposite direction, and a copperl oxide type rectier connected in shunt relation to the couplingmeans on theoutput side thereof in such manner as to by-pass current of polarity zippo'la site to that resulting from breaking of the blastg ing circuit; whereby the impulse as exhibited is ,of sharp unidirectional character.

t. An apparatus for sending and recording a current impulse of irregular fluctuating character produced by the interruption of a blasting circuit,

-graphic impulse recorder arranged .to receive the induced impulse, said recorder being constructed and arranged to record quantitatively impulses applied to it, a half-wave rectiiier connected in the output sidefof the coupling means in series relation thereto, 'and a half-wave rectier connected in shunt relation to the output side of the coupling ineens. said series rectifier being connected so as to pass induced current of polarity resulting from interruption of the blasting circuit `and said shunt rectier being connected so as to bycurrent of opposite polarity; whereby the blasting circuit intervention impulse as recorded is of sharp unidireoti character. 

